At present, LCD or AMOLED is used as a display screen of smart phone in the market, the LCD or AMOLED is an active light-emitting device with high power consumption, and is one of the main power consumption devices of the smart phone, which affects battery life of the smart phone seriously. An LCD or AMOLED screen has high brightness, light emitted by which would stimulate eyes seriously. Using the smart phones for long time would lead to eye fatigue easily, and even cause loss of vision. The backlight projection design of the screen of the smart phones would also make it difficult for user to read under the strong light, and would lead to perspective restrictions.